Reforming



I Alllgfz);194,6v yA. B. -wE|."rY, .JR 2,406,117 I l A 'I REFQRMINGFiled OGL 2A, 1945 mqsr zA-r n .BOILER v srozcz .plan

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1 "L" 3 quent stage of this processas will subsequently appear, or fromsome extraneous source. This `hydrogen is discharged from line II intoline Ill land thereafter with the oil into reactor I2, the `amount ofhydrogen employed being from 1000 to 4000 cubic feet of hydrogen perbarrel of liquid oil. It is pointed out that in reactor I2-I maintain apressure preferably of theorder iof'from `150 to 400 l-bs, per squareinch. It should also be noted that in the type ofV operationcontemplated, the catalyst is in the form of pills, pellets,`Y

extruded lengths, granules, and the like and is supported on the traysT, which trays have foraminous bases. The oil yis fed Ato the. reactorat a rate of say from 0.5 to 2 volumesof'oil per volume of catalyst perhour on a cold oil basis.

Under the conditions stated, the feed stock undergoes transformationv ofthe character indi; cated, and the productY is withdrawn through line Ypart .so that the hydrogen will be more pure as it enters -line II. Thismay be accomplished in any `known manner in equipment not illustrated,for example, the gas in line 30 could be scrubbed with `a narrow-boilingkerosene fraction to preferentiaklly absorb the hydrocarbons and thehydrogen' recycled to I2 would -be substantially pure.

The bottoms from separation drum 42are withdrawnIthrough VlineV 43 anddischarged into a fractionator- 44; from 'which fractionator the productisY recoveredas a side stream through line 5I.. An overhead fractioncontaining hydrogen Vand light hydrocarbons is recovered through lineV52'vandY thisV product may Vbe processed `to recover hydrogen in meansnot shown; for example, it may be scrubbed with kerosene or otherscrubbing,agent-to remove a substantial portion of the hydrocarbonswhereby the hydrogen-is enriched and is rendered suitable for recyclingtoreactor I2. The hydrocarbons themselves may be; stripped fromthesolvent and dehydrogenated tojform'olefns and dioleflns which may beused asintermediatesrfor the, production of aviation gasoline or rubbersubstitutes. l .QA bottoms fraction is recovered through line 55 andrecycled to the 'inlet side of vpump 3 for further use inthe process. Aportion Yof these heavy Ybottoms may be withdrawn through line 58- andVrejected from the system. l In-the foregoing description, I haveoutlined for the purpose of clarity a procedure generally employed inreforming a naphtha in the presence ofv hydrogen and a suitable catalystso that my specific improvements regarding regeneration of the catalystwill be better understood.. Asrindicated,lthe. reforming operation, inspite of the factthat itwas conducted in the presenceV of hydrogen,tends to progressively build up contaminants'on the catalyst in reactorI2. These contaminants vimpair the activity of the catalyst and makeitnecessary tov discontinue the reformingoperation to purify thecatalyst.l This may be accomplished by burning off the contaminant's. Itwill be understood that in .order to maintain continuity of overalloperation it is preferable to provide two or. more reactors I2 so thatwhile the catalyst in one or more reactors is undergoing.regeneration,the on-'stream proc- 4 ess may be carried out in one orfmore of theothers. Y

Another method for maintaining continuity of operation is to inject intothe vapors in line I a i5 powdered catalyst to form a suspension whichis forced through a reaction zone, which suspension Y will then passthrough a separator usually located outside the reactor toQseparatethecatalyst from the reaction products.- The separated cataiO lyst may beregenerated in a regeneration zone vand returned continuously to thereaction Zone in the form of active catalyst, thus maintainingcontinuity of operation, but my process is primarily concerned with thestationary Ibed type of voperation described above employing one or morereactors containing spaced beds of pilled catalyst or a continuous bedof catalyst. As previously indicated, the pressure imposed on thereactants in I2 as indicated in pressure gauge I4 o would beconsiderably elevated and may be as much as 400lbs. per square inch,although lower pressures, such as 190 lbs; per square inch, are oftenused during the reforming operation.- Y Specifically describing myimprovements Vin re- .,5 generating a catalyst,the following procedureis employed. First, the oil supply is discontinued and in so doing, Iclose valve 3l in line II' and open valve32 in line 30 and dischargethrough the reactor the hydrogen and/or recycle gas (con- 3() taininghydrogen) in order to purgeV out of the j catalyst all of thevolatilizable oils, that is to say, the catalyst being an adsorptivesubstance adsorbs normally liquid oils, or at least readily.`

`vaporizable hydrocarbons and these are removedv by owing the recycledgas upwardly through line 33 through the reactor for a period of aboutl5 minutes. The oif gases from the operation are withdrawn through line35 and they may be'sent to an absorption zone (not shown). to recovernormally liquid products therefrom, and there-.- 1' after the hydrogenpurified of hydrocarbons is l recycled to line I I. Following thepurging operation, I close valve 32 in line 30, and I next inject aninert gas, such as'nitrogen or flue gas, via

1:5 line 60, in the reactor to purge the hydrogenVV from the reactor.The purging gas used for dis- Q placing hydrogen from the reactorispreferably a portionV of the spent regeneration gas, orrather the exitgases from a previous regeneration co1- lected at the beginning of saidregeneration in a storage drum 59, and contains Vless than 6% Oxy-- genandV preferably'less than 2% Afree oxygen. Y

`The catalyst is treated with this inert gas, whether it belnitrogenor-spent Yregeneration gas, for a periodof about l5 minutes. ,Boththehydrogen purge and the linert flue gas purge are conducted at about thesame pressure as used during the productive phase of reforming. Thereactor fol,-

lowing these purgings is substantially free of volatile hydrocarbons andhydrogen and is .ready to be treated with an oxygen-'containing gas toburn off the flxed'carbon contaminating the catalyst.

The Voxygen-containing gas, which mayr be v air,

is discharged intothe reactor throlvlghv line vIII located at the bottomcf saidreactorl andv hows up.

wardly therethrough whereit contacts the Ycatalyst and causescombustionlof theucontamfnants.

This regeneration is carried out-atrpressuresA of v the same order andof the same Arange, aswthose- 7o employed during the reforming.yTheoXygen- Numerousl modifications of my invention' fallvWhat I claimis: Y 1. 'I'he method of reforming a hydrocarbon in the presence of` acatalyst which consists essen- 1 vtially of a reducible metal oxide ofgroup VI of l the periodic system carried on an alumina-con- 3tainingbasey and added free hydrogen in which 1 operation the reactiontakes place under super- 1 atmospheric pressure and which operationrequires periodic regeneration of the catalyst, the l improvement whichcomprises subjecting the cataylst after regenerationxto a purgingoperation with free. hydrogen or free hydrogen-containing gas carriedout at pressures substantially less 3 than those employed during thesaid reforming operation. f 2. The method set forth in claim 1 in whichthe I purging operation with free hydrogen-containing ;gas is carriedout at substantially atmospheric pressure.` Y

3. The method set forth in claim 1 in which a feed stock containingmethylcyclohexane is subijected to reforming conditions to producetoluzene.

y '4. The method of producing toluene from a hydrocarbon fractioncontaining methylcyclohexane w'hich comprises contacting the said feedstock With'la reforming catalyst consisting essentially of a reduciblemetal oxide selectedV from the class "consisting of molybdenum oxiderand chromium :oxide carriedon an alumina support, inthe presence ofadded free hydrogen and under reforming conditions of temperature andpressure, with- Qdrawing reaction products, discontinuing the flow `offeed stock to the catalyst, regenerating the catalyst, purging withinert gas and prior to returning the feed stock to the catalyst, purgingthe said catalyst with a free hydrogen-containing gas at pressuressubstantially below those employed during the reforming operation.

5. The method set forth in claim 4 ifi which catalyst is purged with aflue gas at pressures prevailing during the reforming operation andthereafter vpurged with a free hydrogen-contain-Y erationwhether thefeed stock be a more `or less 1 pure compound or whether it be a naphthasuch i v as a cracked or virgin naphtha.

ing gas at pressures not substantially-exceeding Y about 1 atmospheregauge pressure., Y

6.V The method set forth in claim 4 in which following the .purgingWithinert gas the pressure imposed on the catalyst is reduced to aboutatmospheric within a space of from about 5 to 15 minutes.

7. In the method of reforming a normally liquid hydrocarbon oilcontaining naphthenic components under superatmospheric pressure andelevated temperatures and inthe presence of added l free hydrogen and areforming catalyst consisting essentially of ka reducible metal oxideselected from the class consisting of molybdenum oxide and chromiumoxide carried on an alumina support, lthe improvement which comprisespurging the catalyst following the necessary regeneration of saidcatalyst with a free hydrogen-containing gas at pressures not exceedingabout lbs. per square inch gauge pressure until such time as hydrogenappears in large quantities in the exit gas.

8. The method set forth in claim 4 in which following purging With afreev hydrogen-containing gas at reduced pressures the system isrepressured with a gas containing hydrogen.

9. In the process of catalytic reforming of hydrocarbon distillates inthe presence of free hydrogen under superatmospheric pressure in whichthe catalyst consisting essentially of a reducible metal Yoxide selectedfrom the class consisting of molybdenum oxide and chromium oxide carriedon an alumina support, is gradually deactivated by a formation ofcarbonaceous deposits thereon, the steps of regenerating the catalystfor reuse which comprises purging the catalyst of oil Va 1 por bydirecting a current of free hydrogen therethrough,` purging the catalystof hydrogen by L purging the catalyst of oxygen by passing a stream ofinertl gas therethrough, passing the stream of hydrogen 'through thecatalyst and'maintaining a low` pressure below that employed in thehydroforming operation, then building pressure with hydrogen to thelevel employed for hydroforming oil and hydrogen for and thereafteragain recommencing the feed of the hydroforming step. ALBERT B. WELTY,JR.

Disclaimer 2,406,117.-Albert B. Welty, Jr., Mountainside, N. J.REFORMING. Patent dated Aug. 20, 1946. Disclaimer iled Apr. 15, 1949, bythe assignee, vStotmtmct Oil Development Gompel/ny, Hereby disclaimsfrom claims 1, 2, 3, 4, 8, and 9, and each of them, any process of thetype defined in Which the step of purging the catalyst With freehydrogen or free hydrogen-containing gas is not continued until hydrogenbegins to appear in large quantities in the eXit gas.

[Ocial Gazette, May 17, 1949.]

